Scilab Manual for

Optical Communication
by Dr Lochan Jolly
Electrical Engineering
Thakur College of Engineering & Technology1

Solutions provided by
Dr Lochan Jolly
Electrical Engineering
Mumbai, Thakur college of engineering & technology

February 20, 2020

1 Funded by a grant from the National Mission on Education through ICT,

http://spoken-tutorial.org/NMEICT-Intro. This Scilab Manual and Scilab codes
written in it can be downloaded from the ”Migrated Labs” section at the website
http://scilab.in
1
Contents

List of Scilab Solutions 3

1 To calculate the numerical aperture of the optical fiber. 5

2 To calculate the Bending Loss in the optical fiber in the

link. 7

3 To plot the responsivity curve for the given detector mate-

rial. 9

4 To plot the characteristic curve for LED. 11

5 To calculate material dispersion at various wavelength of

operation. 13

6 To do power budgeting for the link for given parameters. 15

7 To do time budgeting for the link for given parameters. 17

8 To calculate fiber parameters (dimensions, refractive index

difference) for single mode operation. 19

2
List of Experiments

Solution 1.1 Numerical aperture . . . . . . . . . . . . . . . . . 5

Solution 2.2 Bending Loss . . . . . . . . . . . . . . . . . . . . 7
Solution 3.3 Responsivity . . . . . . . . . . . . . . . . . . . . . 9
Solution 4.4 LEDcharacteristics . . . . . . . . . . . . . . . . . 11
Solution 5.5 Material dispersion . . . . . . . . . . . . . . . . . 13
Solution 6.6 Power Budgeting . . . . . . . . . . . . . . . . . . 15
Solution 7.7 Time Budgeting . . . . . . . . . . . . . . . . . . . 17
Solution 8.8 Single Mode . . . . . . . . . . . . . . . . . . . . . 19

3
List of Figures

1.1 Numerical aperture . . . . . . . . . . . . . . . . . . . . . . . 6

2.1 Bending Loss . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.1 Responsivity . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4
 Experiment: 1

To calculate the numerical

aperture of the optical fiber.

Scilab code Solution 1.1 Numerical aperture

1 // E x p e r i m e n t no . 1 To c a l c u l a t e t h e n u m e r i c a l
aperture of the o p t i c a l f i b e r .
2 //OS=Windows XP s p 3
3 // S c i l a b v e r s i o n 5 . 4 . 0
4 // s a m p l e v a l u e s
5 // n1 =1.50
6 // n2 =1.47
7 clear ;
8 close ;
9 clc ;
10 n1 = input ( ” e n t e r t h e v a l u e o f c o r e r e f r a c t i v e i n d e x ” )
11 n2 = input ( ” e n t e r t h e v a l u e o f c l a d d i n g r e f r a c t i v e
index ”)
12 delta =( n1 ^2 - n2 ^2) /(2* n1 ^2)
13 NA = n1 * sqrt (2* delta )
14 accept = asind ( NA )
15 disp ( NA , ” n u m e r i c a l a p e r t u r e=” ) ;

5
 Figure 1.1: Numerical aperture

16 disp ( accept , ” a c c e p t a n c e a n g l e=” ) ;

6
 Experiment: 2

To calculate the Bending Loss

in the optical fiber in the link.

Scilab code Solution 2.2 Bending Loss

1 // E x p e r i m e n t no . 2 To c a l c u l a t e t h e Bending L o s s i n
the o p t i c a l f i b e r in the l i n k .
2 //OS=Windows XP s p 3
3 // S c i l a b v e r s i o n 5 . 4 . 0
4 // s a m p l e v a l u e s
5 // n1 =1.50
6 // n2 =1.47
7 //R=1e −2
8 // lambda =0.82
9 clear ;
10 close ;
11 clc ;
12 n1 = input ( ” e n t e r t h e v a l u e o f c o r e r e f r a c t i v e i n d e x=”
)
13 n2 = input ( ” e n t e r t h e v a l u e o f c l a d d i n g r e f r a c t i v e
i n d e x=” )
14 R = input ( ” e n t e r t h e v a l u e o f r a d i u s o f c u r v a t u r e o f

7
 Figure 2.1: Bending Loss

bend i n m=” ) // c u r v a t u r e o f bend

15 lambda = input ( ” e n t e r t h e v a l u e w a v e l e n g t h i n
m i c r o m e t e r=” )
16 c1 =1.2; // c o n s t a n t
17 c2 =0.5 // c o n s t a n t
18 delta =( n1 ^2 - n2 ^2) /(2* n1 ^2) ;
19 Rc =(3* lambda *1 e -6) /(4*3.14*2* delta ) ;
20 alpha = c1 * exp ( - c2 * R ) ;
21 alphadb =10* log ( alpha )
22 disp ( alphadb , ” Bending l o s s i n db=” ) ;
23 disp ( Rc , ” c r i t i c a l r a d i u s i n m=” ) ;

8
 Experiment: 3

To plot the responsivity curve

for the given detector material.

Scilab code Solution 3.3 Responsivity

1 // E x p e r i m e n t no . 3 To p l o t t h e r e s p o n s i v i t y c u r v e f o r
the given d e t e c t o r material .
2 //OS=Windows XP s p 3
3 // S c i l a b v e r s i o n 5 . 4 . 0
4 // s a m p l e v a l u e s
5 // Eg =1.43
6 clear ;
7 close ;
8 clc ;
9 Eg = input ( ” Band gap o f m a t e r i a l s e l e c t e d i n eV=” )
10 e =1.6 e -19;
11 eta =0.65 // quantum e f f i c i e n c y
12 h =6.626 e -34; // p l a n k s c o n s t a n t
13 c =3 e8 // v e l o c i t y o f l i g h t
14 lambdacf = h * c /( Eg * e *1 e -6) ; // w a v e l e n g t h i n m i c r o m e t e r
15 lambda =0:0.25:2 // r a n g e o f w a v e l e n g t h
16 for i =1:9

9
 Figure 3.1: Responsivity

17 if ( lambda ( i ) < lambdacf )

18 responsivity ( i ) = eta * e *1 e -6* lambda ( i ) /( h * c ) ;
19 else responsivity ( i ) =0
20 end
21 end
22 plot2d ( lambda , responsivity ) ;
23 xtitle ( ’ R e s p o n s i v i t y c u r v e ’ , ’ Lambda (um) ’ , ’
R e s p o n s i v i t y ’ );

10
 Experiment: 4

To plot the characteristic curve

for LED.

Scilab code Solution 4.4 LEDcharacteristics

1 // E x p e r i m e n t no . 4 To p l o t t h e c h a r a c t e r i s t i c c u r v e
f o r LED . .
2 //OS=Windows XP s p 3
3 // S c i l a b v e r s i o n 5 . 4 . 0
4 clear ;
5 close ;
6 clc ;
7 h =6.626 e -34; // p l a n k s c o n s t a n t
8 c =3 e8 ; // v e l o c i t y o f l i g h t
9 e =1.6 e -19; // c h a r g e o f e l e c t r o n
10 lambda =0.87 e -6 // w a v e l e n g t h o f l i g h t
11 tr =60 e -9; // r e g e n e r a t i v e r e c o m b i n a t i o n
12 tnr =100 e -9; // non r e g e n e r a t i v e r e c o m b i n a t i o n
13 t = tr * tnr /( tr + tnr ) ;
14 Nint = t / tnr // i n t e r n a l quantum e f f i c i e n c y
15 for i = 1:40
16 L(i)=i;

11
17 pint ( i ) = Nint * i * h * c *1 e -3/( e * lambda ) ; // i i s
c u r r e n t i n amperes
18 end
19
20 plot2d (L , pint ) ;
21 xtitle ( ’ C h a r a c t e r i s t i c s o f LED ’ , ’ C u r r e n t ( Amperes ) ’ ,
’ Power ( Watts ) ’ ) ;

12
 Experiment: 5

To calculate material dispersion

at various wavelength of
operation.

Scilab code Solution 5.5 Material dispersion

1 // E x p e r i m e n t no . 5 To c a l c u l a t e m a t e r i a l d i s p e r s i o n
at various wavelength of operation .
2 //OS=Windows XP s p 3
3 // S c i l a b v e r s i o n 5 . 4 . 0
4 // s a m p l e v a l u e s
5 // L0 =1.3 ( z e r o d i s p e r s i o n w a v e l e n g t h psnm−2km−1)
6 // S0 = 0 . 0 9 5 ( S l o p e a t z e r o d i s p e r s i o n w a v e l e n g t h i n
psnm−1km−1)
7
8 clear ;
9 close ;
10 clc ;
11 L0 = input ( ” e n t e r t h e v a l u e o f z e r o dispersion
w a v e l e n g t h i n um” )
12 S0 = input ( ” e n t e r t h e v a l u e o f S l o p e a t z e r o

13
 d i s p e r s i o n wavelength ”)
13 lambda =0.7:0.1:1.7 // w a v e l e n g t h o f l i g h t
14 MD =( lambda .* S0 /4) .*(1 -( L0 ./ lambda ) .^4) ; // M a t e r i a l
Dispersion
15 plot2d ( lambda , MD ) ;
16 xtitle ( ’ M a t e r i a l D i s p e r s i o n a t v a r i o u s w a v e l e n g t h ’ ,
’ w a v e l e n g t h ( m e t e r s ) ’ , ’ M a t e r i a l D i s p e r s i o n ( psnm−1
km−1) ’ ) ;

14
 Experiment: 6

To do power budgeting for the

link for given parameters.

Scilab code Solution 6.6 Power Budgeting

1 // E x p e r i m e n t no . 6 To do power b u d g e t i n g f o r t h e l i n k
f o r given parameters
2 //OS=Windows XP s p 3
3 // S c i l a b v e r s i o n 5 . 4 . 0
4 // s a m p l e v a l u e s
5 // Ps=13 ( i n p u t power i n dBm)
6 // Pr=−31( s e n s i t i v i t y o f r e c e i v e r )
7 //L=80( L i n k l e n g t h i n Km)
8 // L o s s = 0 . 3 5 ( f i b e r l o s s i n dB/Km)
9 // SL = 0 . 1 ( S p l i c e L o s s i n dB )
10 //CL= 0 . 5 ( c o u p l i n g l o s s i n dB )
11 //EL = 1 . 5 ( e x c e s s l o s s )
12
13 clear ;
14 close ;
15 clc ;
16 Ps = input ( ” Power from s o u r c e i n dBm=” ) ;

15
17 Pr = input ( ” s e n s i t i v i t y o f r e c e i v e r i n dBm=” ) ;
18 L = input ( ” L i n k l e n g t h i n Km=” ) ;
19 Loss = input ( ” f i b e r l o s s i n dB/Km=” ) ;
20 SL = input ( ” S p l i c e L o s s i n dB/Km=” ) ;
21 CL = input ( ” c o u p l i n g l o s s i n dB=” ) ;
22 EL = input ( ” e x c e s s l o s s i n dB=” ) ;
23 Pt = Ps - Pr ;
24 SM = Pt -(2* CL + Loss * L + SL * L )
25 disp ( ”dB” ,SM , ” s y s t e m m a r g i n=” ) ;

16
 Experiment: 7

To do time budgeting for the

link for given parameters.

Scilab code Solution 7.7 Time Budgeting

1 // E x p e r i m e n t no . 7 To do r i s e t i m e b u d g e t i n g f o r t h e
l i n k f o r given parameters
2 //OS=Windows XP s p 3
3 // S c i l a b v e r s i o n 5 . 4 . 0
4 // s a m p l e v a l u e s
5 // t s =10 ( r i s e t i m e o f t h e l e d s o u r c e i n n s )
6 //IMD=6( i n t e r m o d a l d i s p e r s i o n i n n s /Km)
7 //L=10( l i n k l e n g t h i n Km)
8 //PB=2( p u l s e b r o a d e n i n g i n n s /Km)
9 // t d =8( r e s p o n s e t i m e o f d e t e c t o r i n n s )
10 //F=1(1−RZ r e t u r n t o z e r o f o r m a t , 2−NRZ−non r e t u r n
to zero format )
11
12
13 clear ;
14 close ;
15 clc ;

17
16 ts = input ( ” r i s e t i m e o f t h e l e d s o u r c e i n n s=” ) ;
17 IMD = input ( ” i n t e r m o d a l d i s p e r s i o n i n n s /Km=” ) ;
18 L = input ( ” L i n k l e n g t h i n Km=” ) ;
19 PB = input ( ” p u l s e b r o a d e n i n g i n n s /Km=” ) ;
20 td = input ( ” r e s p o n s e t i m e o f d e t e c t o r i n n s=” ) ;
21 disp ( ” D i r e c t o r y 1−RZ r e t u r n t o z e r o
f o r m a t , 2−NRZ−non r e t u r n t o z e r o f o r m a t ” ) ;
22 F = input ( ” Format=” ) ;
23 Tsys =1.1* sqrt ( ts ^2+( L * IMD ) ^2+ td ^2+( L * PB ) ^2) ;
24 if F ==1 then Bt =0.35*1 e3 / Tsys // s i n c e Tsys i s i n
nano s e c and Bt i s e x p r e s s e d i n Mbps )
25 else Bt =0.7*1 e3 / Tsys
26 end
27 disp ( ”Mbps” ,Bt , ”Maximum b i t r a t e f o r t h e l i n k =” ) ;

18
 Experiment: 8

To calculate fiber parameters

(dimensions, refractive index
difference) for single mode
operation.

Scilab code Solution 8.8 Single Mode

1 // E x p e r i m e n t no . 8 To c a l c u l a t e f i b e r p a r a m e t e r s f o r
s i n g l e mode o p e r a t i o n
2 //OS=Windows XP s p 3
3 // S c i l a b v e r s i o n 5 . 4 . 0
4 // s a m p l e v a l u e s
5 // lambda ( 1 ) =8e −6 ( w a v e l e n g t h o f t r a n s m i s s i o n )
6 // r i c = 1 . 4 5 ( r e f r a c t i v e i n d e x o f c o r e )
7 //V= 2 . 4 0 5 (V mumber )
8 // d e l t a = 0 . 0 0 3 ( r e f r a c t i v e i n d e x d i f f e r e n c e )
9
10
11 clear ;
12 close ;

19
13 clc ;
14 lambda =0.8 e -6:0.1 e -6:1.7 e -6;
15 ric = input ( ” r e f r a c t i v e i n d e x o f c o r e=” ) ;
16 V = input ( ”V mumber f o r s i n g l r mode t r a n s m i s s i o n=” ) ;
17 delta = input ( ” r e f r a c t i v e i n d e x d i f f e r e n c e =” ) ;
18 for i =1:10
19 a ( i ) = V * lambda ( i ) /(2*3.14* ric * sqrt (2* delta ) )
20 end
21 plot2d ( lambda , a ) ;
22 xtitle ( ’ Core d a i m e t e r v e r s u s w a v e l e n g t h o f
t r a n s m i s s i o n ’ , ’ Wavelength ( Lambda ) (m) ’ , ’ Core
d i a m e t e r (m) ’ ) ;

20